Currently, over 400 cases of clear cell adenocarcinoma of the vagina and cervix occurring in females born after 1940 have been accessioned into the Registry for Research on Hormonal Transplacental Carcinogenesis. Cases have been identified throughout the United States as well as Australia, Canada, Mexico, and Europe. Intrauterine exposure to DES and similar nonsteroidal estrogens have been uncovered in about two-thirds of the cases with an available maternal history. A peak in the age incidence curve of the DES-related cases has been observed at about 19 years with the age range being 7-30 years. The five-year survival for 400 patients has been 80%. Numerous nonmalignant epithelial changes have been observed. It appears that there has not been an increase in the occurrence of premalignant or malignant squamous cell lesions among the DES exposed. Premature birth has been more common among DES-exposed women. For those in whom there is evidence of a midpregnancy loss or premature ripening of the cervix during pregnancy, a cerclage procedure has been effective in producing a desirable outcome.